Esophagitis is a very common toxicity of radiotherapy (RT). European Organization for the Research and Treatment of Cancer (EORTC) quality of life questionnaire (QLQ)-OES18 can be used to measure the quality of life (QoL) associated with esophageal symptoms. We aimed to translate and validate this questionnaire in Turkish patients. Patients with head and neck cancer (HNC), lung cancer (LC) or esophageal cancer (EC) were administered the EORTC QLQ-C30 and QLQ-OES18 on the 1st, 15th, and last days of RT and at the 3rd month follow-up. Psychometric properties of reliability, validity, scale structure and responsiveness to change were analyzed. Ninety-seven patients were included in the study. All scores in the QLQ-C30, and all but the reflux scores in the QLQ-OES18 were found to change significantly during and after treatment. All correlations of the QLQ-OES18 scale between the 1st and 15th days, 15th and last days, and all but the trouble with coughing score between the last day and follow-up were significantly different. Correlation levels ranged between 33.5-79.9%, 48.7-87.2%, and 0.6-74.8% at each comparison period, respectively. The reliability was evaluated by Cronbach's alpha at each assessment period, and the result was 0.824, 0.889, 0.898, and 0.824 for treatment start, mid-treatment, treatment end, and 3rd month follow-up, respectively. The Turkish version of QLQ-OES18 is a valid tool which can be used independently from the demographic and clinical characteristics of the patients. It is highly reliable to evaluate health-related QoL in patients with esophageal symptoms that are treated for HNC, LC, or EC.